A primer on arrhythmias in patients with hypertrophic cardiomyopathy.

Patients with hypertrophic cardiomyopathy are at risk of atrial and ventricular arrhythmias, yet treatment options for these patients are made almost solely by extrapolation from patients with other diseases. Heart block may be seen spontaneously but is especially prevalent following septal reduction strategies. Atrial fibrillation is the most common arrhythmia in patients with hypertrophic cardiomyopathy. The onset of atrial fibrillation often represents a turning point clinically for patients, marked by substantial functional deterioration and morbidity. Sudden cardiac death is the most common cause of death in the young patient, but still contributes to mortality in older patients. Major risk factors for sudden cardiac death include resuscitated sudden cardiac death, marked hypertrophy, syncope, and family history of sudden cardiac death due to hypertrophic cardiomyopathy. Minor risk factors for sudden cardiac death include nonsustained ventricular tachycardia, and hypotensive response to exercise. Emerging possible risk factors include atrial fibrillation, myocardial ischemia, left ventricular outflow tract obstruction, genetic mutations, left ventricular apical aneurysms, myocardial fibrosis, and end stage disease.